Transportation refrigeration system having multiple fans

ABSTRACT

A transportation refrigeration system includes a refrigeration circuit that includes a compressor, a condenser, a first heat exchanger and a second heat exchanger. A first variable speed fan is associated with the first heat exchanger and a second variable speed fan is associated the second heat exchanger.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/657,259, which was filed on Apr. 13, 2018 and is incorporated herein by reference.

BACKGROUND

This application relates to refrigeration systems having at least two fans for cooling an enclosed cargo space.

Refrigeration systems are known. Generally, a compressor compresses a refrigerant and delivers it into a condenser. The refrigerant is cooled and passes through an expansion valve. The refrigerant is expanded and passes through an evaporator. The evaporator cools air to be delivered into an environment to be conditioned.

One application for such refrigeration systems is in a transportation refrigeration system. As an example, a truck may have a refrigerated trailer. It is known to provide distinct temperatures at distinct compartments within a common trailer. Individual refrigeration circuits are often utilized to provide the distinct temperatures.

SUMMARY

In one exemplary embodiment, a transportation refrigeration system includes a refrigeration circuit that includes a compressor, a condenser, a first heat exchanger and a second heat exchanger. A first variable speed fan is associated with the first heat exchanger and a second variable speed fan is associated the second heat exchanger.

In a further embodiment of any of the above, the first variable speed fan operates independently of the second variable speed fan.

In a further embodiment of any of the above, a first compartment passageway has a first compartment passageway inlet located upstream of the first heat exchanger. The first variable speed fan is located downstream of the first heat exchanger.

In a further embodiment of any of the above, a first nozzle is downstream of the first variable speed fan and has a first compartment outlet.

In a further embodiment of any of the above, a second compartment passageway has a second compartment passageway inlet located upstream of the second heat exchanger. A second variable speed fan is located downstream of the second heat exchanger.

In a further embodiment of any of the above, a second nozzle is downstream of the second variable speed fan and has a second compartment outlet.

In a further embodiment of any of the above, the first compartment outlet is spaced from the second compartment outlet.

In a further embodiment of any of the above, the first variable speed fan includes a plurality of first variable speed fans.

In a further embodiment of any of the above, the second variable speed fan includes a plurality of second variable speed fans.

In a further embodiment of any of the above, the first heat exchanger is in parallel to the second heat exchanger.

In a further embodiment of any of the above, a first expansion device is upstream of the first heat exchanger.

In a further embodiment of any of the above, the first expansion device is a first electronically controlled expansion valve. A controller is configured to control refrigerant flow to the first heat exchanger by controlling the first electronically controlled expansion valve.

In a further embodiment of any of the above, a second expansion device is upstream of the second heat exchanger.

In a further embodiment of any of the above, the second expansion device is a second electronically controlled expansion valve. The controller is configured to control refrigerant flow to the second heat exchanger by controlling the second electronically controlled expansion valve.

In another exemplary embodiment, a method of operating a refrigeration cycle includes the steps of conditioning a first compartment in a cargo space and a first heat exchanger by operating a first variable speed fan at a first speed. Conditioning a second compartment in the cargo space a second heat exchanger by operating a second variable speed fan at a second speed. The first speed is different from the second speed.

In a further embodiment of any of the above, operating the first variable speed fan includes drawing air from the first compartment into a first compartment passageway inlet, over the first heat exchanger and through a first nozzle having a first compartment passageway outlet.

In a further embodiment of any of the above, operating the second variable speed fan includes drawing air from the second compartment into a second compartment passageway inlet, over the second heat exchanger and through a second nozzle having a second compartment passageway outlet spaced from the first compartment passageway outlet.

In a further embodiment of any of the above, refrigerant flow is controlled through a first electronically controlled expansion valve upstream of the first heat exchanger with a controller in electrical communication with the first electronically controlled expansion valve.

In a further embodiment of any of the above, controlling refrigerant flow through a second electronically controlled expansion valve upstream of the second heat exchanger with a controller in electrical communication with the second electronically controlled expansion valve.

In a further embodiment of any of the above, operating the first variable speed fan at a first maximum flow rate and operating a second variable speed fan at a second maximum flow rate that is less than the first maximum flow rate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating a transport refrigeration system.

FIG. 2 is a schematic view of the air flow over a pair of absorption heat exchangers.

DETAILED DESCRIPTION

FIG. 1 illustrates a transport refrigeration system 20 associated with a cargo space 22, such as a refrigerated cargo space. In the illustrated example, the cargo space 22 is divided into a first compartment 22A and a second compartment 22B by a dividing wall 23.

A controller 24 manages operation of the refrigeration system 20 to establish and regulate a desired product storage temperature within the first compartment 22A and the second compartment 22B of the cargo space 22. The cargo space 22 may be the cargo box of a trailer, a truck, a seaboard shipping container or an intermodal container wherein perishable cargo, such as, for example, produce, meat, poultry, fish, dairy products, cut flowers, and other fresh or frozen perishable products, is stowed for transport.

The refrigeration system 20 includes a refrigerant compression device 26, a refrigerant rejection heat exchanger 28, a first expansion device 30A, a second expansion device 30B, a first refrigerant absorption heat exchanger 32A, and a second refrigerant absorption heat exchanger 32B connected in a closed loop refrigerant circuit and arranged in a conventional refrigeration cycle. The first and second expansion devices 30A, 30B can be electrically controlled expansion valves controlled by the controller 24 to regulator refrigerant flow through each of the first and second absorption heat exchangers 32A, 32B, respectively. The refrigeration system 20 also includes one or more fans 34 associated with the rejection heat exchanger 28 and a first and second fan 36A, 36B associated with each of the first and second absorption heat exchangers 32A, 32B. In one example, the first and second absorption heat exchangers 32A, 32B are evaporators.

It is to be understood that other components (not shown) may be incorporated into the refrigerant circuit as desired, including for example, but not limited to, a suction modulation valve, a receiver, a filter/dryer, an economizer circuit.

The rejection heat exchanger 28 may, for example, comprise one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes extending between respective inlet and outlet manifolds. The fan(s) 34 are operative to pass air, typically ambient air, across the tubes of the refrigerant rejection heat exchanger 28 to cool refrigerant vapor passing through the tubes.

The first and second absorption heat exchangers 32A, 32B may, for example, also comprise one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes extending between respective inlet and outlet manifolds. The first and second fans 36A, 36B are operative to pass air drawn from the temperature controlled cargo space 22 across the tubes of the absorption heat exchangers 32A, 32B to heat the refrigerant passing through the tubes and cool the air. The air cooled in traversing the absorption heat exchangers 32A, 32B is supplied back to a respective first and second compartment 22A, 22B in the cargo space 22. Although only a single first and second fan 36A, 36B are shown in the illustrated embodiment, multiple first and second fans 36A, 36B could be associated with the first and second absorption heat exchangers 32A, 32B, respectively.

Prior to entering the refrigerant compression device 26, the refrigerant passes through an outlet valve 38. The outlet valve 38 controls a pressure and state of the refrigerant entering the refrigerant compression device 26. The refrigerant compression device 26 may comprise a single-stage or multiple-stage compressor such as, for example, a reciprocating compressor or a scroll compressor.

In the refrigeration system 20, the controller 24 is configured for controlling operation of the refrigeration system 20 including, but not limited to, operation of the various components of the refrigerant system 20 to provide and maintain a desired operating temperature within the cargo space 22. The controller 24 may be an electronic controller including a microprocessor and an associated memory bank. The controller 24 controls operation of various components of the refrigeration system 20, such as the refrigerant compression device 26, the first and second expansion devices 30A, 30B, the fans 34, 36A, 36B, and the outlet valve 38.

FIG. 2 schematically illustrates air flow from the first and second compartments 22A, 22B through a respective first and second absorption heat exchanger 32A, 32B. The air flow from the first compartment 22A flows through a first compartment passageway 40A and back into the first compartment 22A. The first compartment passageway 40A includes a first compartment passageway inlet 42A that accepts air from the first compartment 22A into the first compartment passageway 40A. From the first compartment passageway inlet 42A, the air is drawn by the first fan 36A over the first absorption heat exchanger 32A and into a first nozzle 44A. From the first nozzle 44A, the air exits the first compartment passageway 40A through a first compartment passageway outlet 46A and travels back into the first compartment 22A.

Similarly, the air flow from the second compartment 22B flows through a second compartment passageway 40B and back into the second compartment 22B. The second compartment passageway 40B includes a second compartment passageway inlet 42B that accepts air from the second compartment 22B into the second compartment passageway 40B. From the second compartment passageway inlet 42B, the air is drawn by the second fan 36B over the second absorption heat exchanger 32B and into a second nozzle 44B. From the second nozzle 44B, the air exits the second compartment passageway 40B through a second compartment passageway outlet 46B and travels back into the second compartment 22B.

In one example, the first and second compartments 22A, 22B could be unequally sized in volume. When the first and second compartments are unequally sized, the fan 36A, 36B associated with the larger of the first and second compartments 22A, 22B could run at a high speed than the fan 36A, 36B associated with the smaller of the two compartments. Alternatively, the first and second compartments 22A, 22B could be the same size but have different cooling requirements.

Because the first and second fans 36A, 36B operate independently of each other and at variable speeds, the refrigeration system 20 is able to operate more efficiently by operating the first and second fans 36A, 36B at an optimal speed that does not exceed demand for the respective first and second compartments 22A, 22B. Additionally, one of the first and second fans 36A, 36B could be rotating while the other of the first and second fans 36A, 36B could be stationary. In addition to varying speed between the first and second fans 36A, 36B, the first and second fans 36A, 36B can have different maximum flow rates to meet the cooling needs of the first and second compartments 22A, 22B. This can be achieved by changing a geometry, such as diameter and/or pitch, of the fan blades of the individual first and second fans 36A, 36B.

The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims. 

What is claimed is:
 1. A transportation refrigeration system comprising: a refrigeration circuit including a compressor, a condenser, a first heat exchanger, and a second heat exchanger, wherein a first variable speed fan is associated with the first heat exchanger and a second variable speed fan is associated the second heat exchanger.
 2. The transportation refrigeration system of claim 1, wherein the first variable speed fan operates independently of the second variable speed fan.
 3. The transportation refrigeration system of claim 1, further comprising a first compartment passageway having a first compartment passageway inlet located upstream of the first heat exchanger and the first variable speed fan located downstream of the first heat exchanger.
 4. The transportation refrigeration system of claim 3, including a first nozzle downstream of the first variable speed fan having a first compartment outlet.
 5. The transportation refrigeration system of claim 4, further comprising a second compartment passageway having a second compartment passageway inlet located upstream of the second heat exchanger and a second variable speed fan located downstream of the second heat exchanger.
 6. The transportation refrigeration system of claim 5, including a second nozzle downstream of the second variable speed fan having a second compartment outlet.
 7. The transportation refrigeration system of claim 6, wherein the first compartment outlet is spaced from the second compartment outlet.
 8. The transportation refrigeration system of claim 7, wherein the first variable speed fan includes a plurality of first variable speed fans.
 9. The transportation refrigeration system of claim 8, wherein the second variable speed fan includes a plurality of second variable speed fans.
 10. The transportation refrigeration system of claim 1, wherein the first heat exchanger is in parallel to the second heat exchanger.
 11. The transportation refrigeration system of claim 10, further comprising a first expansion device upstream of the first heat exchanger.
 12. The transportation refrigeration system of claim 11, wherein the first expansion device is a first electronically controlled expansion valve and a controller is configured to control refrigerant flow to the first heat exchanger by controlling the first electronically controlled expansion valve.
 13. The transportation refrigeration system of claim 12, further comprising a second expansion device upstream of the second heat exchanger.
 14. The transportation refrigeration system of claim 13, and the second expansion device is a second electronically controlled expansion valve and the controller is configured to control refrigerant flow to the second heat exchanger by controlling the second electronically controlled expansion valve.
 15. A method of operating a refrigeration cycle comprising the steps of: conditioning a first compartment in a cargo space a first heat exchanger by operating a first variable speed fan at a first speed; and conditioning a second compartment in the cargo space a second heat exchanger by operating a second variable speed fan at a second speed; wherein the first speed is different from the second speed.
 16. The method of claim 15, wherein operating the first variable speed fan includes drawing air from the first compartment into a first compartment passageway inlet, over the first heat exchanger and through a first nozzle having a first compartment passageway outlet.
 17. The method of claim 16, wherein operating the second variable speed fan includes drawing air from the second compartment into a second compartment passageway inlet, over the second heat exchanger and through a second nozzle having a second compartment passageway outlet spaced from the first compartment passageway outlet.
 18. The method of claim 15, further comprising: controlling refrigerant flow through a first electronically controlled expansion valve upstream of the first heat exchanger with a controller in electrical communication with the first electronically controlled expansion valve.
 19. The method of claim 18, further comprising: controlling refrigerant flow through a second electronically controlled expansion valve upstream of the second heat exchanger with a controller in electrical communication with the second electronically controlled expansion valve.
 20. The method of claim 15, further comprising: operating the first variable speed fan at a first maximum flow rate; and operating a second variable speed fan at a second maximum flow rate that is less than the first maximum flow rate. 